GNGTS 2022 - Atti del 40° Convegno Nazionale

370 GNGTS 2022 Sessione 2.2 structure to determine the natural frequencies and the corresponding shapes of the vibrating modes. Monitoring of vibration frequencies serve as a useful reference for evaluating the degradation in stiffness or strength of the structure, and even for identifying possible damages in the structure, say, due to long-term overloading and impacts by heavy trucks or earthquake shakings (Yangh et al. , 2004). The development of a dynamic monitoring system therefore requires a knowledge of the natural frequencies and the shapes of the vibration modes of the structure and it is possible to obtain it by taking advantage of the vibrations induced by wind and traffic (Magalhães et al. , 2008). Among the significant sources of environmental excitation there is also the earthquake that produces a transient stress, the spectrum of which varies from one event to another. The limits of applicability of this excitation are linked to the fact that an earthquake is a sporadic event and can be detected with permanent monitoring systems (Aceti and Bressan, 2014). The recorded data will allow to determine the natural frequencies and of the relative forms of the modes of vibration for the evaluation the dynamic behavior of the structure and to calculate the response of the structure following any dynamic stress acting on known characteristics such as an earthquake or a dynamic load of exercise. Acknowledgements. The authors thank Dr. Giuseppe Macaluso and all the other members of ANAS team for support in the activities. References Aceti M. and Bressan M. D.; 2014: il valore delle prove dinamiche nel collaudo di infrastrutture civili. Thesis in civil engineering, Università degli Studi di Milano. Branca S., Coltelli M., Groppelli M. and Lentini F.; 2011. Geological Map of Etna Volcano . Ital. J. Geosci., 130, n.3. Calvi G. M., Pinho R. and Crowley H.; 2006: State-of-the-knowledge on the period elongation of RC buildings during strong ground shaking. In Proceedings of the 1st European conference of earthquake engineering and seismology, Geneva, Switzerland, paper (Vol. 1535). Cantero D., Hester, D., and Brownjohn, J.; 2017: Evolution of bridge frequencies and modes of vibration during truck passage . Eng. Struct., 152, 452-464, doi: 10.1016/j.engstruct.2017.09.039 D.M. 17/10/2018. Norme Tecniche per le Costruzioni (NTC 2018) . G.U. n.42 del 20/02/2018, suppl. ord. n. 8, cap. 9, p.299. Magalhães F., Cunha A. and Caetano E.; 2008: Dynamic monitoring of a long span arch bridge . Eng. Struct., 30, 3034- 3044. Meletti C., Montaldo V., Stucchi M., and Martinelli F.; 2006: Database della pericolosità sismica MPS04 . Istituto Nazionale di Geofisica e Vulcanologia (INGV). https://doi.org/10.13127/sh/mps04/db Ren W., Zatar W. and Harik I.; 2004: Ambient vibration-based seismic evaluation of a continuous girder bridge . Eng. Struct., 26, 5, pp. 631-640, doi: 10.1016/j.engstruct.2003.12.010 Yang Y.B., Lin C.W. and Yau J.D.; 2004: Extracting bridge frequencies from the dynamic response of a passing vehicle . J. Sound Vib., 272, pp. 471-493, doi:10.1016/S0022-460X(03)00378-X.